Mixing apparatus and method

ABSTRACT

A mixing apparatus comprising a stator housing having a cylindrical inner wall defining a mixing chamber having an inlet and an outlet leading thereto. A rotor is supported for rotatable and reciprocal motion within the mixing chamber and defines a cylindrical rotor wall spaced from the stator inner wall. Drive means and coupling means are provided for transmitting rotatable and axial reciprocating motion to the rotor. The stator inner wall is provided with rows of spaced apart projections thereon protruding into the mixing chamber. The rotor is also provided with rows of spaced apart rotor blades which are arranged in a predetermined manner to pass between the stator projections on the inner wall of the stator. The coupling means is arranged to provide a cycloidal motion to the rotor whereby each rotor blade will pass between adjacent stator projections and wipe against them on the upward motion and pass between rows of projections on the downward motion.

[ Jan. 29, 197% MIXING APPARATUS AND METHOD Stefan Leslaw Toczyski, 8336Place Chanceaux, Ville DAniou, Quebec, Canada [22] Filed: June 27, 1972[21] Appl. No.: 266,639

[76] Inventor:

[30] Foreign Application Priority Data July 1, 1971 Great Britain30,918/71 [52] US. Cl. 259/5 [51] int. Cl Boll 7/16 [58] Field of Search259/191, 5,2, 21, 40,192, 259/193, 64, 4

[5 6] References Cited Primary Examiner-Robert W. Jenkins A mixingapparatus comprising a stator housing having a cylindrical inner walldefining a mixing chamber having an inlet and an outlet leading thereto.A rotor is supported for rotatable and reciprocal motion within themixing chamber and defines a cylindrical rotor wall spaced from thestator inner wall. Drive means and coupling means are provided fortransmitting rotatable and axial reciprocating motion to the rotor. Thestator inner wall is provided with rows of spaced apart projectionsthereon protruding into the mixing chamber. The rotor is also providedwith rows of spaced apart rotor blades which are arranged in apredetermined manner to pass between the stator projections on the innerwall of the stator. The coupling means is arranged to provide acycloidal motion to the rotor whereby each rotor blade will pass betweenadjacent stator projections and wipe against them on the upward motionand pass between rows of projections on the downward motion.

8 Claims, 6 Drawing Figures MHZ/I05 Ml i sat/0s m/ H547 ZONE BASESVAPOURS 70 GAS SUEZ/BEEP I 70 GAS SCRUBBEI? PATENIED JAN 2 9 I974 sum u0F 5 FIG. 4

PATENTEI] JAN 23 I974 SHEET 5 0F 5 MIXING APPARATUS AND METHODBACKGROUND or INVENTION 1. Field of the Invention This invention relatesto a mixing apparatus and method.

In particular the apparatus of the invention is specially applicable tomechanical mixing, chemical reactions, kneading, crystallizing, drying,evaporating, ho-

mogenizing, degassing and feeding. The invention is useful for mixingliquids, plastic materials and solid materials and combinations ofthese.

2. Description of Prior Art The prior art is replete with attempts toprovide better mixing equipment. Most have shortcomings in that theyfail to provide for mixing a homogeneous mass of components on acontinuous process basis. Often lumps appear in the mixed product.

The action of mixing may best be compared with that of a person kneadingflour and water to make dough for bread. The action of pushing,squeezing, pulling and overlapping occur within the persons hands.

I The prior art attempts to reproduce this action to provide a rotorwith blades rotating about a longitudinal axis and at the same timeexecuting a reciprocating motion. This produces a sinusoidal motion ofrotor blades between projections on the inside of a stator. Because ofthe rotor and stator blades geometric disposition, this action islimited to only one movement in either direction, that is one rotary andone reciprocating motion. Further, this design requires large clearancesbetween the rotor blades and the stator projections, resulting inpassing lumps without proper mixing. Further, the prior art lacks otheraspects of control of the mixing process.

SUMMARY OF INVENTION The present invention aims to overcome thedisadvantages mentioned and to provide positive advantages as will beevident from the following description.

From a broad aspect, the present invention provides a mixing apparatuscomprising a stator housing having a cylindrical inner wall defining amixing chamber having an inlet and an outlet leading thereto. A rotor issupported for rotatable and reciprocal motion within the mixing chamberand defines a cylindrical rotor wall spaced from the stator inner wall.Drive means and coupling means are provided for transmitting rotatableand axial reciprocating motion to the rotor. The stator inner wall isprovided with rows of spaced apart projections thereon protruding intothe mixing chamber. The rotor is also provided with rows of spaced apartrotor blades which are arranged in a predetermined manner to passbetween the stator projections on the inner wall of the stator. Thecoupling means is arranged to provide a cycloidal motion to the rotorwhereby each rotor blade will pass between adjacent stator projectionsand wipe against them on the upward motion and pass between rows ofprojections on the downward motion.

BRIEF DESCRIPTION OF DRAWINGS Having thus generally described theinvention, it will be referred to in more detail by reference to theaccompanying drawings, which show preferred embodiments and in which:

FIG. 1 is a vertical cross-section through a mixer according to theinvention;

FIG. 2 is an enlarged vertical cross-section, partly in elevation,through a preferred drive used in a mixer, as shown in FIG. 1;

FIG. 3 is an enlarged vertical cross-section, similar to that of FIG. 2,an alternative preferred drive assembly;

FIG. 4 is an enlarged vertical cross-section through a furtheralternative form of drive;

FIG. 5 is a diagram illustrating the motion of the blades produced bythe drive of FIGS. 2 or 3;

FIG. 6 is a diagram showing the general arrangement of the drive gearsof FIGS. 2 and 3 specially illustrating their motion.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring more particularly to FIG.1, the mixer is made up of the following main parts. An elongatedvertically disposed stator body A is supported in a conventional manner,in this case hung from a floor or ceiling beam B to enclose a mixingchamber. The body A extends from a special drive C, as will be describedlater in more detail to an outlet D. Within the body is a rotor Econnected to a shaft F from the drive C.

In the particular form shown, the rotor E is in the form of a hollowshell having an upper part and a lower part 17 of reduced diameter. Theparts 15 and 17 are adapted to receive heating or cooling fluid.

The rotor E carries external mixing blades G. The body A is providedwith heating jackets 19 and 20 and with inward projections which may bebolts or blades J.

At a convenient location towards the upper part of the body A areprovided inlets 21 and 23 for solids and liquids respectively. Gas andvapor outlets are shown at 24 and 25 and 27.

GENERAL OPERATION In general operation the liquid and/or solid materialsto be mixed are fed into the inlets 21 and 23. A typical example wouldbe an aqueous sulfuric acid and fluor spar. The materials gravitatewithin the mixing chamber in the stator A as the rotor E is in motion bythe drive C. The material is acted on by the blades G in conjunctionwith the projections J and is propelled downwards by the action of theblades through the outlet D.

The rotor E is rotated and at the same time reciprocated in anup-and-down direction, in a special manner, made possible by the driveC, as will be described in detail. This imparts to the blades a specialpath, as will be later described, and consequently produces the uniquemixing action, characteristic of the invention.

DETAILED DESCRIPTION OF DRIVE Referring to FIG. 2 which shows apreferred drive, this drive includes having a main housing K, a primemover, which in this case, is an electric motor 39. The motor 39 isconnected to a drive shaft 41 through a coupling 43 and a stub shaft 45.The drive shaft is of special design and has a hollow part 47terminating in a flange 4-9 which has an annular toothed extremity orgear part 51. The gear part 51 meshes with secondary gears 53, each ofwhich has an outwardly extending shaft 55 and an inwardly extendingshaft 57. The shaft 55 is mounted in a cage 59 through ball bearings 61.

The cage is in turn mounted on bearings 63 within a part of the housingK.

Carried on the shaft 57 are bearings 65 mounted between plates 67 and69, attached to a collar 71, mounted on a shaft 73. The shaft 73 extendswithin the hollow part 47 of the shaft 41 and is slidable up and downwithin this hollow shaft on bearings 75 and 77. The shaft 41 carries agear 79 which drives a gear 81 through a belt or other transmission 83.In turn the gear 81 drives a' shaft 85 mounted in bearings in the mainhousing K. The lower end of the shaft 85 carries a gear 87 which mesheswith a gear 89 which has an outwardly extending flange 91 which has anannular toothed portion 93 which engages with the gear 53.

In operation the rotation of the shaft 41 by the motor 39, through thegearing arrangement, causes rotation of the gear 93 and the gear 51, soas to cause rotation of the gears 53 and the shaft 57.

The alternative construction shown in FIG. 3 is similar to that shown inFIG. 2 and similar numbers have been given to the parts except that theyhave been raised by one hundred and similar letters have been used forsimilar parts with the addition of a prime sign. The difference betweenthe constructions is that in FIG. 3 there is no external drive throughgears 79 which, in turn, drives the gear 93. But the gear 193 is fixedto a base formed by an annular boss 194 on the housing K The apparatusshown in FIG. 4 is adapted to generate a different curve through which apoint on the stator would move as a result of the special motionimparted to the mixer by this drive. This construction will be describedin terms of its operation.

A motor (not shown) drives shaft 201 which in turn drives a shaft 203coupled through a train of gears M appropriately journalled on shafts inthe gearbox L, which in turn drives an outward shaft 205, which drivesthe gear 207 meshing with the gear 209 on a shaft 211. The shaft 211drives a crank 213 to impart to it a reciprocal motion. The crank 213 inturn imparts reciprocal motion to a shaft 215, through a yoke 217, whichreciprocates a coupling 219 which in turn is connected to the mixerrotor (not shown) through a shaft 221.

Rotary motion to the shaft 215 is imparted as follows. From the geartrain M is driven a gear 223, mounted on spider 225 which rotates onbearings 227 and 229 on the shaft 215. The spider 225 carries a yoke 231which has channels which engage bearings 233 mounted on a spider 235keyed to the shaft 215 with key 237.

It is thus seen that there is imparted to the shaft 215 both areciprocal up-and-down motion as well as a rotary motion causing therotor sections G to move in such a way that a point on its surface willdescribe a sinusoidal curve.

The arrangement as shown in FIG. 2 may be produced to give a combinationof movements of gears 53 and by thus the shaft 73, namely, by:

1. Rotating gears 51 and 93 in the same direction and at the sameperipheral speed, the gear 53 is locked between gears 51 and 93. Theshaft 73 is only rotated at the speed of the shaft 41 with noup-and-down movement.

2. Rotating gears 51 and 93 in the opposite direction, but at equalperipheral speed, the gear 53 will rotate around the center of the shaft55 but will not execute circular motion around the shaft 73.

The main motion imparted to the shaft 73 is the upand-down motion.

3. Rotating gear 51 but holding gear 93, see FIG. 3, the gear 53 impartsthe composite motion to the shaft 73 which rotates at the speed of theshaft 41 and slides up and down at the ratio of R and r.

4. Rotating the gears 51 and 93 but varying the peripheral speed anddirection from maximum speed in, for example, the left direction throughzero speed to maximum speed in the opposite direction, right directiongives a variation of both movements from rotation only to predominantlysliding motion and all movements in between.

Through proper engagement, similar motions can be achieved with thedrive arrangement shown in FIG. 4.

For drives to be used with the mixer where stator has teeth or bladearrangement, the motion of the rotor must be made to fit the relativemovement of rotor and stator blades.

FIG. 5 shows the path of a rotor blade as described on the circumferenceof the stator. This path is a curve, as designed and controlled by thedrive on FIGS. 1 to 3. The teeth on the stator are arranged in such away that each rotor blade passes between individual pairs of teeth onthe upward motion and between rows of teeth on the downward motion.

The mixing action is as follows. When the downward motion blades move inbetween two rows of teeth the material is kneaded between the rotor andstator teeth and pushed in the downward direction. At the same time therotary motion is imparted. The rotary motion is composed with thedownward motion into cycloidal motion. The downward stroke causeskneading action between the rotor blades and the stator blades. Theupward stroke causes a shearing and wiping motion as the rotor bladesmove between two consecutive teeth.

FIG. 6 shows diagram of gears 51 and 53, as presented in FIG. 2. Theratio of radius R of gear 51, to the radius r of gear 53 in FIG. 2(applies to FIG. 3)

defines the number of sliding movements of the shaft 73 per onerevolution. Because the rotor blades must always clear the blades orteeth of the stator, therefore the ratio of R to r must be so chosenthat each rotor blade will exactly repeat its consecutive movement inspace in relation to its previous movement. This condition can be metwhen the number of revolutions of small gear 53 per one revolution ofthe large gear 51 is a whole number.

I claim:

1. A mixing apparatus comprising a stator housing having a cylindricalinner wall defining a mixing chamber, said mixing chamber having aninlet and an outlet, a rotor supported for rotatable and reciprocalmotion within said mixing chamber and having a cylindrical rotor wallspaced from said stator inner wall, drive means, coupling meansconnected between said drive means and rotor for transmitting arotatable and axial reciprocating motion to said rotor, said statorinner wall having rows of spaced apart projections thereon protrudinginto said mixing chamber, said rotor having rows of spaced apart rotorblades arranged to pass between said stator projections, said couplingmeans being arranged to provide a cycloidal motion to said rotor wherebyeach rotor blade will pass between adjacent stator projections and wipeagainst them on the upward motion and pass between rows of projections.on the downward motion, said coupling means comprising a first andsecond annular toothed gear, said first and second gears beingpositioned in opposed spaced apart relationship on a common central axisand having identical radius and number of teeth, opposed circularsecondary gears in toothed engagement between said first and secondannular gears, a rotor shaft supported on said central axis andconnected to said secondary gears, said first annular gear beingrotatably driven by said drive means to impart rotary motion to saidrotor shaft and upward and downward motion through said secondary gears.

2. A mixing apparatus as claimed in claim 1 wherein said statorprojections are stator blades adapted to pass in close proximity to thesurfaces of said rotor blade.

3. A mixing apparatus as claimed in claim 2 wherein a material isintroduced to said mixing chamber in said inlet and removed through saidoutlet, said material being kneaded between said rotor and stator bladesand pushed towards said outlet during said downward motion, said upwardmotion of said rotor imparting a shearing and wiping action to saidmaterial as each said rotor blades moves between adjacent stator blades.

4. A mixing apparatus as claimed in claim 1 wherein said second annulargear is fixed and said secondary gears impart said rotary and upward anddownward motion to said rotor shaft as said secondary gears rotate aboutthe circumference of said first and second annular gears.

5. A mixing apparatus as claimed in claim 1 wherein said second annulargear is driven by said drive means at the same peripheral speed and inopposite direction to said first annular gear causing said secondarygears to rotate about its central transverse axis and to thereby impartupward and downward motion to said rotor shaft.

6. A mixing apparatus as claimed in claim 1 wherein said first andsecond annular gears are driven at the same peripheral speed and in thesame direction by said drive means, said secondary gears being lockedwithin said first and second annular gears whereby said secondary gearsimpart a rotary motion to said rotor shaft.

7. A mixing apparatus as claimed in claim 1 wherein said first andsecond annular gears are rotated at varying peripheral speed in onedirection and at varying speed in the opposite direction, saiddirections being reversed when said drive means is stopped.

8. A mixing apparatus as claimed in claim 1 wherein said secondary gearsare each supported by a central transverse shaft supported in a cagedisposed in a horidownward motion to said rotor shaft.

1. A mixing apparatus comprising a stator housing having a cylindricalinner wall defining a mixing chamber, said mixing chamber having aninlet and an outlet, a rotor supported for rotatable and reciprocalmotion within said mixing chamber and having a cylindrical rotor wallspaced from said stator inner wall, drive means, coupling meansconnected between said drive means and rotor for transmitting arotatable and axial reciprocating motion to said rotor, said statorinner wall having rows of spaced apart projections thereon protrudinginto said mixing chamber, said rotor having rows of spaced apart rotorblades arranged to pass between said stator projections, said couplingmeans being arranged to provide a cycloidal motion to said rotor wherebyeach rotor blade will pass between adjacent stator projections and wipeagainst them on the upward motion and pass between rows of projectionson the downward motion, said coupling means comprising a first andsecond annular toothed gear, said first and second gears beingpositioned in opposed spaced apart relationship on a common central axisand having identical radius and number of teeth, opposed circularsecondary gears in toothed engagement between said first and secondannular gears, a rotor shaft supported on said central axis andconnected to said secondary gears, said first annular gear beingrotatably driven by said drive means to impart rotary motion to saidrotor shaft and upward and downward motion through said secondary gears.2. A mixing apparatus as claimed in claim 1 wherein said statorprojections are stator blades adapted to pass in close proximity to thesurfaces of said rotor blade.
 3. A mixing apparatus as claimed in claim2 wherein a material is introduced to said mixing chamber in said inletand removed through said outlet, said material being kneaded betweensaid rotor and stator blades and pushed towards said outlet during saiddownward motion, said upward motion of said rotor imparting a shearingand wiping action to said material as each said rotor blades movesbetween adjacent stator blades.
 4. A mixing apparatus as claimed inclaim 1 wherein said second annular gear is fixed and said secondarygears impart said rotary and upward and downward motion to said rotorshaft as said secondary gears rotate about the circumference of saidfirst and second annular gears.
 5. A mixing apparatus as claimed inclaim 1 wherein said second annular gear is driven by said drive meansat the same peripherAl speed and in opposite direction to said firstannular gear causing said secondary gears to rotate about its centraltransverse axis and to thereby impart upward and downward motion to saidrotor shaft.
 6. A mixing apparatus as claimed in claim 1 wherein saidfirst and second annular gears are driven at the same peripheral speedand in the same direction by said drive means, said secondary gearsbeing locked within said first and second annular gears whereby saidsecondary gears impart a rotary motion to said rotor shaft.
 7. A mixingapparatus as claimed in claim 1 wherein said first and second annulargears are rotated at varying peripheral speed in one direction and atvarying speed in the opposite direction, said directions being reversedwhen said drive means is stopped.
 8. A mixing apparatus as claimed inclaim 1 wherein said secondary gears are each supported by a centraltransverse shaft supported in a cage disposed in a horizontal plane, afurther shaft secured to said secondary gear offset from said centralshaft and attached to a collar mounted on said rotor shaft, saidsecondary gears when rotating causing said further shaft to rotate aboutsaid central shaft to thereby impart said upward and downward motion tosaid rotor shaft.